1. Field of the Invention
The present invention relates to a private branch exchange (PBX) system, and more particularly, to an apparatus and process of transferring call charges during call forwarding.
2. Description of the Related Art
A PBX system generally provides telephone usage information such as call start time, call duration, and call charge when an extension subscriber communicates with an external subscriber through an office line. In this PBX system, when a speech path is formed between a first extension subscriber and an external subscriber through the office line and then a call is forwarded to a second extension subscriber, the first extension subscriber is charged a call charge prior to the call forwarding, and the second extension subscriber is charged a call charge subsequent to call forwarding.
In the conventional PBX system, though the first subscriber originates a call to an external subscriber through an office line and forwards the call to the second extension subscriber, and the second subscriber occupies a substantial part of the call, the first and second extension subscribers are separately charged the call charges according to their call durations. Therefore, to generate billing for the second extension subscriber, the separate charges should inconveniently be added.
An exemplar of the contemporary art, Oman (U.S. Pat. No. 4,072,827, Telephone Patching Apparatus, Feb. 7, 1978) discloses an apparatus for bridging external calls such as an incoming call to a dialed out call in a private branch exchange system. Melampy et al. (U.S. Pat. No. 5,402,472, Automated Attendant for any Combination of PBX, CENTREX, and Single-line Telephones, Mar. 28, 1995) discloses call transfer operations in various telephone systems including a private branch exchange system (PBX).
Burd et al. (U.S. Pat. No. 5,432,845, Post Answer Telephone Call Redirection or Rerouting, Jul. 11, 1995) discloses a method of billing forwarded calls. A third party calls an 800 area code telephone subscriber phone. The original extension receiving the call then forwards the call to second extension. In Burd et al. '845, the original extension is charged only for the time used by that subscriber and the remainder of charges are placed on the second extension.
Greenspan (U.S. Pat. No. 5,517,560, Call Billing and Measurement Methods for Redirected Calls, May 14, 1996) discloses a method for generating two billing records for a redirected call. When a call is forwarded from one call network to another, two billing records are generated for time used on each telephone. The charge is then combined to form a single billing record which is sent to the billing center for processing. This method, however does not shift the charges. Greenspan '560 just generates one bill record for the entire call which leaves it up to the billing center to analyze.
Gupta (U.S. Pat. No. 4,788,719, Telephone Call Charge Allocation Arrangement, Nov. 29, 1988) discloses a method of charging forwarded telephone calls. Concerning a call forwarded from station one to station two, the Gupta '719 invention allocates charges between station one and station two according to the duration of the call.
None of the aforementioned patents shows a method of transferring all of the charges to the telephone receiving the forwarded call. A method of transferring all charges are necessary in situations such as a lodging house where an operator is used to connect to a call and then forward the call to a lodger. The lodger is the person using the telephone system and all the charges should go to the lodger. No separate calculation would be needed with a call charge transfer process. Also, such a method would be useful in an office environment where outside line access is limited. An office worker may have to ask the office operator to make a call to outside the office and forward the call. The office worker making the request should be charged for the entire duration of the call. Furthermore, such a method is useful in an environment where a customer calls a toll free 800 area code company information line. The user pays no cost, however the company must pay the fee. This becomes a problem when the customer has called the wrong department. Department A may have to transfer the call to department B which has its own toll free 800 billing. A charge transfer method would correct any improper billing of such charges. Another example concerns a client calling collect to a company. An operator will accept the call and then forward to the employee handling such client. The call charges should then be transferred to the employee. A call charge transfer process and apparatus is needed to properly bill the above circumstances. A call charge transfer method would also facilitate any further paper corrections of the charges. The unnecessary extra paper work and analysis will waste time and money.